Hi OP, sounds like toddler diarrhoea to me. Sorry for all the people saying you shouldn't be frustrated, I've been there and it's relentless. Also makes potty training really difficult so you are right to question it.
My son started with frequent and very soft poos after he turned roughly 1, and we didn't think much of it until it started to be relentless. He then went through a period of very watery stools, up to 8 times a day when he was 18 months. Nursery sent him home understandably, but there was nothing else wrong with him so we went to the GP - he also had an extremely sore bum from all the poos. They did some tests and diagnosed him with toddler diarrhoea.
We did some work ourselves in trying to eliminate what the trigger was for him - and turns out its very high fibre foods - e.g. weetabix, shreddies. Cut that out and it made a big difference, back to 3 ish poos a day and no more sore bum.
Fast forward to age 2.5 when we tried potty training - and we realised that his stools were still too loose for him to have any control over his poos. So we stopped training and looked at his diet again. We removed cows milk and subbed in oat or soya - and wow it made a huge difference - he's pooing actual stools for the first time since he was about 1. Potty training was a success.
He's now almost 3, and weetabix etc still will set him off - he's on the toilet a lot if he manages to steal some of nanas weetabix (who often forgets he can't have it 🙄). We saw a peadiatrician a while ago about something else but chatted about his toddler diarrhoea, and he said he will grow out of it at some point, so we can try and slowly reintroduce milk and the high fibre foods when we are ready. We're in no rush though, he is still able to have other diary products (yogurt, cheese etc) so we have no concerns over his calcium intake etc.
Hope this is helpful - good luck!